Manufacture of molded articles



De- 3, 1940- w. l. TAYLOR ETAL 2,223,538

MANUFACTURE oF MOLDED ARTICLES 1 Filed oct. 9, 1937' wenn.

. Patented 3,- 1940 UNl'rEosTATl-:s PATENT oFF-lcs 2,223,538

MANUFACTURE or Momnn ARTICLES William Ivan Taylor and Leslie Brisbane Gibbin.

Spondon, near merby,

Oeianesc Corporation of of Delaware England, assignors to america, a corporation l Application october 9. 1937, soi-uu No. 168,131v

l rn Gmc mmm November- 6, 193e s claims. (chia-4s) This invention vrelates to improvements in the manufacture of molded articles and-particularly 1 position in s mom, the surface or which bears protuberances of Athe .required dimensions to give pores of the desired character in the surface of the product. Thus, the dimensions of the protuberances may be similar to those of the o' pores in natural sponges, for example a quarter 'toa half an inch or more in diameter, or they maybe considerably smaller, for example of the order of 1 or 2 mms. Preferably, the surface of the mold is also sand-blasted or roughened in 5 some other suitable manner. The present invention includes both` molds having surfaces bearing protuberances and also processes for the production of porous articles'by means of such molds.

The present invention is of particular value in 3 the manufacture of regenerated cellulose sponges from cellulose acetate and other organic esters of cellulose asis described in U. S. Patent No. 2,085,052. The ,manufacture of spch articles may be carried 'out by means of molds having 35 protuberances using compositions such as are described in this speciilcation and effecting saponicaticn as described therein. For example, sponge-like may be obtained -by shaping a composition -consisting of about ilve parts of 4 cellulose acetate, fifteen parts of acetone or other solvent andeighty parts of salt crystals of a diameter' of about a quarter of an inch and a small proportion, for example about one part of coto ton linters. This composition is shaped in a s mold, the surfaces-of which have protuberances of suitable dimensions. The shaped composition'is dried, e. g. ata temperature of about 1097 @andthe dried msssisthen extracted repeatedly with water'in order to remove the sol- 'rno' porous mw obmnod n my say e. g. by treating it for about ho s with 10% causticsoda. n l

may be continued until the mass in completely saponliied. or it may be inu termpted when only partial ssponincatlcn has other strong base.

' composition comes into contact with the alkaline been effected, e. g.,the structure has been sa nifled to about three quarters of its depth. may

be carried out by means of caustic soda or other inorganic base, e. g. sodium silicate, or with methylamine, ethylene diamineor other organic f base.

' In order to facilitate initial setting of the composition the surface of the mold may be ldressed with an alkaline dressing, for example a strongly alkaline soft soap, a solution of sodium sililli cate or a thin paste containing caustic soda or When the cellulose acetate material on the surface of the mold the surface layers of the composition are saponied and are l5 'thus rendered insoluble/in the solvent presentin the composition, so, that their structure is xed. This method-,of hxing the structure of a shaped composition is not, of course, conilned to the manufacture of sponges using molds such .as 20 form the subject of the present invention, but may be applied quite generally to the manufacture of molded articles from compositions having a basis of suitable -saponiable substances,

e. g. cellulose acetate and other vorganic esters 25 of cellulose and polymerised vinyl acetate, whether or not the mold surfaces bear protuberances. Y

Instead of using common salt to form the porous structure of the sponge or other article'30 any other suitable substances may be employed, for example sodium sulphate, sodium borate, sodium carbonate, ammonium carbonate, sodium sulphite or bisulphite or magnesium sulphate. 1 Alternatively, the porous structure' of the mate'- 35 rials may be produced by introducing bubbles of air or other gas into the composition.

While waterl is the most suitable substance to use in order to remove any. soluble substances employed to produce the pores, other liquids, for o example alcohol or benzene, may, if desired, be employed for the Vproduction of the pores in conjunction with organiccompounds or other suitl able substances which are soluble therein.

In general,I proportions of cellulose` acetate or 5 other suitable base, solvent and salt or other soluble substances ofthe order of those given above Y are most suitablff but the constituents may be employed inother proportions if desired; For example, the solventcontent of the composition 50 described above may be reduced before molding until the proportion of solvent to cellulose acetate 'is of the order of 3:2 or even 1:1. The particles of salt or. other substance employed may, 'for example, have a diameter of one-sixteenth to a g5 quarter of an inch or more. For further information with regard to the production of the articial sponges reference is made to U. S. Pat'- ent No. 2,085,052.

Examples of suitable molds according to the present invention are illustrated in the accompanying drawing, wherein- Figure 1 is a vertical of mold,

Figure-2 is an end view of the mold,

Figure 3 is a vertical cross-section of another form of mold, and l Figure 4 is a vertical cross-section of the same mold on the line 4-4'.

Referring to Figures 1 and 2 the mold consists of three similar portions 5, 6 and 1 forming the side of the mold, and two end portions 8 and 9.

The interior surface I0 of the mold is provided.

with a large number of small protuberances II. 'I'his mold-is suitable for the production of artificial sponges resembling natural sea sponges.

Figures 3 and 4 show a mold suitable for 'the production of artificial loofahs, which consists of A three side portions I2, I3 and and two end portions I5 and I 6 whichvare keyed into the side portions as shown. The end portions are provided with protuberances I1, and the interior `surfaces I8 of the side portions are provided with a large number of linear protuberances I9 giving the effect of crossed fibre marks on the finished product.

While the process and apparatus of the present .invention are particularly valuable in the manufacture of artificial Sponges from celluloseacetate and other organic esters of cellulose they are not limitedthereto, but are applicable tothemanufacture of porous articles in general from suitable compositions, e. g.- compositions containing cellulose xanthate.

to secure by Letters Patent is:

cross-section of one form 1. Processfor the production of molded articles, which comprises shaping and setting a. composition containing a normally solid saponiableplastion containing an organic ester of cellulose ina mold, the molding surface of which carries a tic substance selected from thegroup consisting of organic esters of cellulose and polymerized vinyl.

dressing comprising an alkaline saponifying agent whereby the surface of the product is saponied.

3. Process for the production of molded articles, which comprises shaping and setting a composition containing cellulose acetate in a mold, the molding surface of which carries a dressing comprising an alkaline saponifying agent whereby the surface of the product is saponifled.

4. Process for the production 'of molded articles, which comprises shapingand setting a composition containing an organic ester of cellulose in a mold, the molding surface of Awhich c ar- -ries a dressing comprising an alkaline saponifying agent whereby the surface of the product is saponied, and thereafter further saponifying the product.

5. Process for the production ofl molded articles, which comprises shaping and setting a suitticles.

IVAN TAYLOR. LESLIE BRISBANE GIeBms. 

